1
|
Kabus J, Cunze S, Dombrowski A, Karaouzas I, Shumka S, Jourdan J. Uncovering the Grinnellian niche space of the cryptic species complex Gammarus roeselii. PeerJ 2023; 11:e15800. [PMID: 37551343 PMCID: PMC10404395 DOI: 10.7717/peerj.15800] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2023] [Accepted: 07/05/2023] [Indexed: 08/09/2023] Open
Abstract
BACKGROUND The discovery of cryptic species complexes within morphologically established species comes with challenges in the classification and handling of these species. We hardly know to what extent species within a species complex differ ecologically. Such knowledge is essential to assess the vulnerability of individual genetic lineages in the face of global change. The abiotic conditions, i.e., the Grinnellian niche that a genetic lineage colonizes, provides insights into how diverse the ecological requirements of each evolutionary lineage are within a species complex. MATERIAL AND METHODS We sampled the cryptic species complex of the amphipod Gammarus roeselii from Central Germany to Greece and identified genetic lineages based on cytochrome c oxidase subunit I (COI) barcoding. At the same time, we recorded various abiotic parameters and local pollution parameters using a series of in vitro assays to then characterize the Grinnellian niches of the morphospecies (i.e., Gammarus roeselii sensu lato) as well as each genetic lineage. Local pollution can be a significant factor explaining current and future distributions in times of increasing production and release of chemicals into surface waters. RESULTS We identified five spatially structured genetic lineages in our dataset that differed to varying degrees in their Grinnellian niche. In some cases, the niches were very similar despite the geographical separation of lineages, supporting the hypothesis of niche conservatism while being allopatrically separated. In other cases, we found a small niche that was clearly different from those of other genetic lineages. CONCLUSION The variable niches and overlaps of different dimensions make the G. roeselii species complex a promising model system to further study ecological, phenotypic and functional differentiation within this species complex. In general, our results show that the Grinnellian niches of genetically distinct molecular operational taxonomic units (MOTUs) within a cryptic species complex can differ significantly between each other, calling for closer inspection of cryptic species in a conservational and biodiversity context.
Collapse
Affiliation(s)
- Jana Kabus
- Department Aquatic Ecotoxicology, Johann Wolfgang Goethe Universität Frankfurt am Main, Frankfurt am Main, Germany
| | - Sarah Cunze
- Department of Integrative Parasitology and Zoophysiology, Johann Wolfgang Goethe Universität Frankfurt am Main, Frankfurt am Main, Germany
| | - Andrea Dombrowski
- Department Aquatic Ecotoxicology, Johann Wolfgang Goethe Universität Frankfurt am Main, Frankfurt am Main, Germany
| | - Ioannis Karaouzas
- Institute of Marine Biological Resources and Inland Waters, Hellenic Centre for Marine Research, Anavyssos, Greece
| | - Spase Shumka
- Faculty of Biotechnology and Food, Agricultural University of Tirana, Tirana, Albania
| | - Jonas Jourdan
- Department Aquatic Ecotoxicology, Johann Wolfgang Goethe Universität Frankfurt am Main, Frankfurt am Main, Germany
| |
Collapse
|
2
|
Derby AP, Huff Hartz KE, Fuller NW, Landrum PF, Reeve JD, Poynton HC, Connon RE, Lydy MJ. Effects of temperature and salinity on bioconcentration and toxicokinetics of permethrin in pyrethroid-resistant Hyalella azteca. CHEMOSPHERE 2022; 299:134393. [PMID: 35337826 DOI: 10.1016/j.chemosphere.2022.134393] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/30/2021] [Revised: 02/24/2022] [Accepted: 03/19/2022] [Indexed: 06/14/2023]
Abstract
Recent studies demonstrated pyrethroid resistance associated with voltage-gated sodium channel mutations in populations of the epibenthic amphipod, Hyalella azteca. Resistant populations were able to tolerate and bioconcentrate pyrethroids at concentrations significantly higher than toxic levels for non-resistant populations. In conjunction with elevated bioconcentration potential, environmental alteration particularly as a result of global climate change is anticipated to significantly alter abiotic parameters including temperature and salinity. These changes are expected to influence uptake and biotransformation of contaminants. Thus, the aims of the current study were a) to examine the bioconcentration potential of permethrin in two pyrethroid-resistant clades of H. azteca and b) assess the influence of temperature and salinity changes on toxicokinetic parameters. Two pyrethroid-resistant clades of H. azteca were exposed to 14C-permethrin at three salinities (0.2, 1.0 and 6.0 practical salinity units (PSU)) and temperatures (18, 23 and 28 °C). Tests were conducted for up to 36 h and uptake, elimination and biotransformation rates were calculated. Both populations demonstrated bioconcentration factors (BCFs) between five and seven times greater than published data for non-resistant H. azteca, with significant differences between clades. Calculated BCF values were comparable to field populations of resistant H. azteca, emphasizing the potential for elevated pyrethroid bioconcentration in the natural environment and increased exposure for predators consuming pyrethroid-resistant aquatic invertebrates. Alterations to temperature and salinity had no statistically significant effect on uptake or parent compound half-life in either population, though biotransformation was elevated at higher temperatures in both populations. Salinity had a variable effect between the two populations, with lower BCF values at 1.0 PSU in clade D H. azteca and greater BCFs at 6.0 PSU in clade C H. azteca. This is the first study to demonstrate the potential for future climate scenarios to influence toxicokinetics in pyrethroid-resistant aquatic organisms.
Collapse
Affiliation(s)
- Andrew P Derby
- Center for Fisheries, Aquaculture and Aquatic Sciences and Department of Zoology, Southern Illinois University, Carbondale, IL, 62901, USA
| | - Kara E Huff Hartz
- Center for Fisheries, Aquaculture and Aquatic Sciences and Department of Zoology, Southern Illinois University, Carbondale, IL, 62901, USA
| | - Neil W Fuller
- Center for Fisheries, Aquaculture and Aquatic Sciences and Department of Zoology, Southern Illinois University, Carbondale, IL, 62901, USA
| | - Peter F Landrum
- Center for Fisheries, Aquaculture and Aquatic Sciences and Department of Zoology, Southern Illinois University, Carbondale, IL, 62901, USA
| | - John D Reeve
- Department of Zoology, Southern Illinois University, Carbondale, IL, 62901, USA
| | - Helen C Poynton
- School for the Environment; University of Massachusetts; Boston, Massachusetts, 02125, USA
| | - Richard E Connon
- School of Veterinary Medicine, University of California, Davis, Davis, CA, 95616, USA
| | - Michael J Lydy
- Center for Fisheries, Aquaculture and Aquatic Sciences and Department of Zoology, Southern Illinois University, Carbondale, IL, 62901, USA.
| |
Collapse
|
3
|
Romero-Blanco A, Alonso Á. Laboratory versus wild populations: the importance of population origin in aquatic ecotoxicology. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2022; 29:22798-22808. [PMID: 35041167 DOI: 10.1007/s11356-021-17370-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/29/2021] [Accepted: 10/29/2021] [Indexed: 06/14/2023]
Abstract
The origin of the populations used in ecotoxicological bioassays (from nature (wild populations) or from cultures (laboratory populations)) could have a key influence on the sensitivity of the tested species to different toxicants. However, the available information on this subject is scarce. To assess the likely influence of the population origin (wild vs. laboratory) of species-genus on the toxicant tolerance, we performed a quantitative review of the ECOTOX database, from which we collected the effective concentrations for a wide range of compounds (metals and organics), endpoints, and exposure times. We found a general trend of lower sensitivity of wild populations to toxicants than laboratory populations, although sensitivity was dependent on species and toxicant groups. This suggests that the results of bioassays with laboratory populations may overestimate the toxicity of most of the compounds. Our study highlights the relevance of the origin of the populations in the determination of the sensitivity of species to toxicants. This study also warns about the biases in the species and toxicants used in ecotoxicology, which may lead to an underrepresentation of the biodiversity and the toxicological context of aquatic ecosystems.
Collapse
Affiliation(s)
- Alberto Romero-Blanco
- Facultad de Ciencias, Departamento de Ciencias de La Vida, Unidad de Ecología, Biological Invasions Research Group, Universidad de Alcalá, Plaza de San Diego S/N, 28805, Alcalá de Henares, Madrid, Spain.
| | - Álvaro Alonso
- Facultad de Ciencias, Departamento de Ciencias de La Vida, Unidad de Ecología, Biological Invasions Research Group, Universidad de Alcalá, Plaza de San Diego S/N, 28805, Alcalá de Henares, Madrid, Spain
| |
Collapse
|
4
|
Heaton A, Milligan E, Faulconer E, Allen A, Nguyen T, Weir SM, Glaberman S. Variation in copper sensitivity between laboratory and wild strains of Caenorhabditis elegans. CHEMOSPHERE 2022; 287:131883. [PMID: 34818820 DOI: 10.1016/j.chemosphere.2021.131883] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/14/2021] [Revised: 08/09/2021] [Accepted: 08/11/2021] [Indexed: 06/13/2023]
Abstract
Ecological risk assessments of chemicals are frequently based on laboratory toxicity data from a small number of model species that may be reared in labs for years or decades. These populations can undergo many processes in the lab including artificial selection, founder effect, and genetic drift, and may not adequately represent their wild counterparts, potentially undermining the goal of protecting natural populations. Here we measure variation in lethality to copper chloride among strains of an emerging model species in toxicology, Caenorhabditis elegans. We tested four wild strains from Chile, Germany, Kenya, and Madeira (Portugal) against several versions of the standard laboratory N2 strain from Bristol, UK used in molecular biology. The four wild strains were more sensitive than any of the N2 strains tested with copper. We also found that the standard N2 strain cultured in the laboratory for >1 year was less sensitive than a recently cultured N2 strain as well as a cataloged ancestral version of the N2 strain. These results suggest that toxicologists should be cognizant of performing toxicity testing with long-held animal cultures, and should perhaps use multiple strains as well as renew cultures periodically in the laboratory. This study also shows that multi-strain toxicity testing with nematodes is highly achievable and useful for understanding variation in intra- and interspecific chemical sensitivity.
Collapse
Affiliation(s)
- Andrew Heaton
- Department of Biology, University of South Alabama, Mobile, AL, USA; Grand Bay National Estuarine Research Reserve, Moss Point, MS, USA
| | - Emma Milligan
- Department of Biology, University of South Alabama, Mobile, AL, USA
| | | | - Andrew Allen
- Department of Biology, University of South Alabama, Mobile, AL, USA
| | - Timothy Nguyen
- Department of Biology, University of South Alabama, Mobile, AL, USA
| | - Scott M Weir
- Department of Biology, Queens University of Charlotte, Charlotte, NC, USA
| | - Scott Glaberman
- Department of Biology, University of South Alabama, Mobile, AL, USA; Department of Environmental Science & Policy, George Mason University, Fairfax, VA, USA.
| |
Collapse
|
5
|
Desiderato A, Mamos T, Rewicz T, Burzynski A, Mucciolo S. First Glimpse at the Diverse Aquaporins of Amphipod Crustaceans. Cells 2021; 10:3417. [PMID: 34943925 PMCID: PMC8699810 DOI: 10.3390/cells10123417] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2021] [Revised: 11/30/2021] [Accepted: 12/02/2021] [Indexed: 12/31/2022] Open
Abstract
The importance of aquaporins (AQPs) in the transport of water and solutes through cell membranes is well recognized despite being relatively new. To date, despite their abundance, diversity, and presence in disparate environments, amphipods have only been mentioned in studies about the AQPs of other animals and have never been further investigated. In this work, we aimed to recover from public data available AQPs of these crustaceans and reconstruct phylogenetic affinities. We first performed BLAST searches with several queries of diverse taxa against different NCBI databases. Then, we selected the clades of AQPs retrieving the amphipod superfamily Gammaroidea as monophyletic and ran phylogenetic analyses to assess their performances. Our results show how most of the AQPs of amphipods are similar to those of other crustaceans, despite the Prip-like displayed different paralogs, and report for the first time a putative Aqp8-like for arthropods. We also found that the candidate genes of Prip-like, Bib-like, Aqp12-like, and Glp-like help solve deeper relationships in phylogenies of amphipods while leaving uncertainties in shallower parts. With our findings, we hope to increase attention to the study of amphipods as models for AQP functioning and evolution.
Collapse
Affiliation(s)
- Andrea Desiderato
- Department of Invertebrate Zoology and Hydrobiology, University of Lodz, Banacha 12/16, 90-237 Łódź, Poland; (T.M.); (T.R.); (S.M.)
| | - Tomasz Mamos
- Department of Invertebrate Zoology and Hydrobiology, University of Lodz, Banacha 12/16, 90-237 Łódź, Poland; (T.M.); (T.R.); (S.M.)
| | - Tomasz Rewicz
- Department of Invertebrate Zoology and Hydrobiology, University of Lodz, Banacha 12/16, 90-237 Łódź, Poland; (T.M.); (T.R.); (S.M.)
| | - Artur Burzynski
- Department of Genetics and Marine Biotechnology, Polish Academy of Sciences, Institute of Oceanology, Powstańców Warszawy 55, 81-712 Sopot, Poland;
| | - Serena Mucciolo
- Department of Invertebrate Zoology and Hydrobiology, University of Lodz, Banacha 12/16, 90-237 Łódź, Poland; (T.M.); (T.R.); (S.M.)
| |
Collapse
|
6
|
Subba M, Keough MJ, Kellar C, Long S, Miranda A, Pettigrove VJ. Potamopyrgus antipodarum has the potential to detect effects from various land use activities on a freshwater ecosystem. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2021; 287:117563. [PMID: 34147782 DOI: 10.1016/j.envpol.2021.117563] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/06/2021] [Revised: 05/17/2021] [Accepted: 06/06/2021] [Indexed: 06/12/2023]
Abstract
Identifying risks to ecosystems from contaminants needs a diversity of bioindicators, to understand the effects of these contaminants on a range of taxa. Molluscs are an ideal bioindicator because they are one of the largest phyla with extremely high ecological and economic importance. The aim of this study was to evaluate if laboratory bred Potamopyrgus antipodarum has the potential to show the impact of contaminants from various land use activities and degree of pollution on a freshwater ecosystem. We assessed the impact of contaminants arising from runoff and direct discharges in Merri Creek by measuring organism level responses (survival, growth, and reproduction), and sub-organism level responses (glutathione S-transferase (GST) activity, lipid peroxidation (LPO) activity and catalase (CAT) activity) in snails after 28-d of deployment at nine sites in Merri Creek and one site in Cardinia Creek. In Merri Creek, the top two sites were reference sites (with low impact from human activities), while the rest were impact sites (impacted by various anthropogenic land uses). Cardinia Creek (an additional reference site) had lower human activity. High concentrations of heavy metals, nutrients, and/or synthetic pyrethroids (bifenthrin) dominated these sites, which are likely to have contributed towards the negative responses observed in the snails. There was little influence from environmental conditions and site location on the endpoints because we found a similar response at an additional reference site compared to the reference sites in Merri Creek. At the organism level, reproduction increased and/or reduced, while CAT was affected at the sub-organism level. Potamopyrgus antipodarum has the potential to be a sensitive bioindicator for Australian conditions because the snails responded to varying concentrations of contaminants across different land use activities and showed similar sensitivity to P. antipodarum found in other regions of the globe and other bioindicators.
Collapse
Affiliation(s)
- Maita Subba
- Centre for Anthropogenic Pollution Impact and Management (CAPIM), School of Biosciences, University of Melbourne, Parkville, VIC, 3010, Australia.
| | - Michael J Keough
- Centre for Anthropogenic Pollution Impact and Management (CAPIM), School of Biosciences, University of Melbourne, Parkville, VIC, 3010, Australia
| | - Claudette Kellar
- Aquatic Environmental Stress Research Group (AQUEST), School of Science, RMIT University, PO Box 71, Bundoora, VIC, 3083, Australia
| | - Sara Long
- Aquatic Environmental Stress Research Group (AQUEST), School of Science, RMIT University, PO Box 71, Bundoora, VIC, 3083, Australia
| | - Ana Miranda
- Aquatic Environmental Stress Research Group (AQUEST), School of Science, RMIT University, PO Box 71, Bundoora, VIC, 3083, Australia
| | - Vincent J Pettigrove
- Aquatic Environmental Stress Research Group (AQUEST), School of Science, RMIT University, PO Box 71, Bundoora, VIC, 3083, Australia
| |
Collapse
|
7
|
Wang N, Kunz JL, Cleveland DM, Steevens JA, Hammer EJ, Van Genderen E, Ryan AC, Schlekat CE. Evaluation of Acute and Chronic Toxicity of Nickel and Zinc to 2 Sensitive Freshwater Benthic Invertebrates Using Refined Testing Methods. ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY 2020; 39:2256-2268. [PMID: 32761946 DOI: 10.1002/etc.4841] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/11/2020] [Revised: 06/03/2020] [Accepted: 07/30/2020] [Indexed: 06/11/2023]
Abstract
The US Environmental Protection Agency (USEPA) is reviewing the protectiveness of the national ambient water quality criteria (WQC) for nickel (Ni) and zinc (Zn) and compiling toxicity databases to update the WQC. An amphipod (Hyalella azteca) and a unionid mussel (Lampsilis siliquoidea) have shown high sensitivity to Ni and Zn in previous studies. However, there remained uncertainties regarding the influence of test duration (48 vs 96 h) and the presence and absence of food in acute exposures with the amphipod, and there were also concerns about poor control of amphipod growth and reproduction and mussel growth in chronic exposures. We conducted acute 48- and 96-h water-only toxicity tests to evaluate the influence of feeding and test durations on the toxicity of dissolved Ni and Zn to the amphipod; we also used recently refined test methods to conduct chronic Ni and Zn toxicity tests to evaluate the sensitivity of the amphipod (6-wk exposure) and the mussel (4- and 12-wk exposures). The 96-h 50% effect concentrations (EC50s) of 916 µg Ni/L and 99 µg Zn/L from acute amphipod tests without feeding decreased from the 48-h EC50s by 62 and 33%, respectively, whereas the 96-h EC50s of 2732 µg Ni/L and 194 µg Zn/L from the tests with feeding decreased from the 48-h EC50s by 10 and 26%, indicating that the presence or absence of food had apparent implications for the 96-h EC50. Our chronic 6-wk EC20s for the amphipod (4.5 µg Ni/L and 35 µg Zn/L) were 50 to 67% lower than the 6-wk EC20s from previous amphipod tests, and our chronic 4-wk EC20s for the mussel (41 µg Ni/L and 66 µg Zn/L) were similar to or up to 42% lower than the 4-wk EC20s from previous mussel tests. The lower EC20s from the present study likely reflect more accurate estimates of inherent sensitivity to Ni and Zn due to the refined test conditions. Finally, increasing the chronic test duration from 4 to 12 wk substantially increased the toxicity of Zn to the mussel, whereas the 4- and 12-wk Ni effect needs to be re-evaluated to understand the large degree of variation in organism responses observed in the present study. Environ Toxicol Chem 2020;39:2256-2268. © 2020 SETAC.
Collapse
Affiliation(s)
- Ning Wang
- Columbia Environmental Research Center, US Geological Survey, Columbia, Missouri
| | - James L Kunz
- Columbia Environmental Research Center, US Geological Survey, Columbia, Missouri
| | - Danielle M Cleveland
- Columbia Environmental Research Center, US Geological Survey, Columbia, Missouri
| | - Jeffery A Steevens
- Columbia Environmental Research Center, US Geological Survey, Columbia, Missouri
| | - Edward J Hammer
- Water Quality Branch, US Environmental Protection Agency, Chicago, Illinois
| | | | - Adam C Ryan
- Water Quality Branch, US Environmental Protection Agency, Chicago, Illinois
| | | |
Collapse
|
8
|
Wang N, Dorman RA, Ivey CD, Soucek DJ, Dickinson A, Kunz BK, Steevens JA, Hammer EJ, Bauer CR. Acute and Chronic Toxicity of Sodium Nitrate and Sodium Sulfate to Several Freshwater Organisms in Water-Only Exposures. ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY 2020; 39:1071-1085. [PMID: 32113188 DOI: 10.1002/etc.4701] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/26/2019] [Revised: 01/31/2020] [Accepted: 02/25/2020] [Indexed: 06/10/2023]
Abstract
Elevated nitrate (NO3 ) and sulfate (SO4 ) in surface water are of global concern, and studies are needed to generate toxicity data to develop environmental guideline values for NO3 and SO4 . The present study was designed to fill existing gaps in toxicity databases by determining the acute and/or chronic toxicity of NO3 (tested as NaNO3 ) to a unionid mussel (Lampsilis siliquoidea), a midge (Chironomus dilutus), a fish (rainbow trout, Oncorhynchus mykiss), and 2 amphibians (Hyla versicolor and Lithobates sylvaticus), and to determine the acute and/or chronic toxicity of SO4 (tested as Na2 SO4 ) to 2 unionid mussels (L. siliquoidea and Villosa iris), an amphipod (Hyalella azteca), and 2 fish species (fathead minnow, Pimephales promelas and O. mykiss). Among the different test species, acute NO3 median effect concentrations (EC50s) ranged from 189 to >883 mg NO3 -N/L, and chronic NO3 20% effect concentrations (EC20s) based on the most sensitive endpoint ranged from 9.6 to 47 mg NO3 -N/L. The midge was the most sensitive species, and the trout was the least sensitive species in both acute and chronic NO3 exposures. Acute SO4 EC50s for the 2 mussel species (2071 and 2064 mg SO4 /L) were similar to the EC50 for the amphipod (2689 mg SO4 /L), whereas chronic EC20s for the 2 mussels (438 and 384 mg SO4 /L) were >2-fold lower than the EC20 of the amphipod (1111 mg SO4 /L), indicating the high sensitivity of mussels in chronic SO4 exposures. However, the fathead minnow, with an EC20 of 374 mg SO4 /L, was the most sensitive species in chronic SO4 exposures whereas the rainbow trout was the least sensitive species (EC20 > 3240 mg SO4 /L). The high sensitivity of fathead minnow was consistent with the finding in a previous chronic Na2 SO4 study. However, the EC20 values from the present study conducted in test water containing a higher potassium concentration (3 mg K/L) were >2-fold greater than those in the previous study at a lower potassium concentration (1 mg K/L), which confirmed the influence of potassium on chronic Na2 SO4 toxicity to the minnow. Environ Toxicol Chem 2020;39:1071-1085. © 2020 SETAC.
Collapse
Affiliation(s)
- Ning Wang
- Columbia Environmental Research Center, US Geological Survey, Columbia, Missouri, USA
| | - Rebecca A Dorman
- Columbia Environmental Research Center, US Geological Survey, Columbia, Missouri, USA
| | - Christopher D Ivey
- Columbia Environmental Research Center, US Geological Survey, Columbia, Missouri, USA
| | - David J Soucek
- Illinois Natural History Survey, University of Illinois, Urbana-Champaign, Illinois, USA
| | - Amy Dickinson
- Illinois Natural History Survey, University of Illinois, Urbana-Champaign, Illinois, USA
| | - Bethany K Kunz
- Illinois Natural History Survey, University of Illinois, Urbana-Champaign, Illinois, USA
| | - Jeffery A Steevens
- Illinois Natural History Survey, University of Illinois, Urbana-Champaign, Illinois, USA
| | - Edward J Hammer
- Water Quality Branch, US Environmental Protection Agency, Chicago, Illinois, USA
| | - Candice R Bauer
- Water Quality Branch, US Environmental Protection Agency, Chicago, Illinois, USA
| |
Collapse
|
9
|
Grabner D, Sures B. Amphipod parasites may bias results of ecotoxicological research. DISEASES OF AQUATIC ORGANISMS 2019; 136:123-134. [PMID: 31575839 DOI: 10.3354/dao03355] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Amphipods are commonly used test organisms in ecotoxicological studies. Nevertheless, their naturally occurring parasites have mostly been neglected in these investigations, even though several groups of parasites can have a multitude of effects, e.g. on host survival, physiology, or behavior. In the present review, we summarize the knowledge on the effects of Microsporidia and Acanthocephala, 2 common and abundant groups of parasites in amphipods, on the outcome of ecotoxicological studies. Parasites can have significant effects on toxicological endpoints (e.g. mortality, biochemical markers) that are unexpected in some cases (e.g. down-regulation of heat shock protein 70 response in infected individuals). Therefore, parasites can bias the interpretation of results, for example if populations with different parasite profiles are compared, or if toxicological effects are masked by parasite effects. With the present review, we would like to encourage ecotoxicologists to consider parasites as an additional factor if field-collected test organisms are analyzed for biomarkers. Additionally, we suggest intensification of research activities on the effects of parasites in amphipods in connection with other stressors to disentangle parasite and pollution effects and to improve our understanding of parasite effects in this host taxon.
Collapse
Affiliation(s)
- Daniel Grabner
- Aquatic Ecology and Centre for Water and Environmental Research, University of Duisburg-Essen, 45141 Essen, Germany
| | | |
Collapse
|
10
|
Soucek DJ, Mount DR, Dickinson A, Hockett JR. Influence of dilution water ionic composition on acute major ion toxicity to the mayfly Neocloeon triangulifer. ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY 2018; 37:1330-1339. [PMID: 29297606 PMCID: PMC6034637 DOI: 10.1002/etc.4072] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/03/2017] [Revised: 10/31/2017] [Accepted: 12/23/2017] [Indexed: 05/13/2023]
Abstract
Field and laboratory studies have shown that mayflies (Ephemeroptera) tend to be relatively sensitive to elevated major ion concentrations, but little is known about how ionic composition influences these responses. The present study evaluated the acute toxicity of major ion salts to the mayfly Neocloeon triangulifer over a range of background water quality conditions. The mayfly was particularly sensitive to Na2 SO4 , with the median lethal concentration (LC50) of 1338 mg SO4 /L being lower than LC50s reported for 7 other species at that hardness. Increasing hardness of the dilution water from 30 to 150 mg/L (as CaCO3 ) resulted in doubling of LC50s for sodium salts, and an approximately 1.5-fold increase in LC50 for MgSO4 . Potassium salt toxicity was not strongly influenced by hardness, consistent with findings for other species. When hardness was held constant but the Ca to Mg ratio was manipulated, the ameliorative effect on Na2 SO4 and NaCl did not appear as strong as when hardness was varied; but for MgSO4 the amelioration relative to Ca activity was similar between the 2 experiments. The toxicity of K salts to N. triangulifer was similar to Na salts on a millimolar basis, which contrasts with several other species for which K salts have been much more toxic. In addition, the toxicity of KCl to N. triangulifer was not notably affected by Na concentration, as has been shown for Ceriodaphnia dubia. Finally, plotting LC50s in terms of ion activity (Cl, SO4 , Na, Mg, or K) over the range of Ca activities in dilution water resulted in significant positive relationships, with comparable slopes to those previously observed for C. dubia over the same range of Ca activities. Environ Toxicol Chem 2018;37:1330-1339. © 2018 SETAC.
Collapse
Affiliation(s)
- David J Soucek
- Illinois Natural History Survey, Champaign, Illinois, USA
| | - David R Mount
- Mid-Continent Ecology Division, US Environmental Protection Agency, Duluth, Minnesota, USA
| | - Amy Dickinson
- Illinois Natural History Survey, Champaign, Illinois, USA
| | - J Russell Hockett
- Mid-Continent Ecology Division, US Environmental Protection Agency, Duluth, Minnesota, USA
| |
Collapse
|
11
|
Fišer C, Robinson CT, Malard F. Cryptic species as a window into the paradigm shift of the species concept. Mol Ecol 2018; 27:613-635. [DOI: 10.1111/mec.14486] [Citation(s) in RCA: 263] [Impact Index Per Article: 43.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2017] [Revised: 12/12/2017] [Accepted: 12/13/2017] [Indexed: 12/15/2022]
Affiliation(s)
- Cene Fišer
- SubBio Lab; Department of Biology; Biotechnical Faculty; University of Ljubljana; Ljubljana Slovenia
| | - Christopher T. Robinson
- Department of Aquatic Ecology; Eawag; Dübendorf Switzerland
- Institute of Integrative Biology; ETH Zürich; Zürich Switzerland
| | - Florian Malard
- Université Lyon; Université Claude Bernard Lyon 1; CNRS; ENTPE; UMR5023 LEHNA Villeurbanne France
| |
Collapse
|
12
|
Weston DP, Poynton HC, Major KM, Wellborn GA, Lydy MJ, Moschet C, Connon RE. Using Mutations for Pesticide Resistance to Identify the Cause of Toxicity in Environmental Samples. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2018; 52:859-867. [PMID: 29240994 DOI: 10.1021/acs.est.7b05071] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Traditional Toxicity Identification Evaluations (TIE) are applied to identify causal agents in complex environmental samples showing toxicity and rely upon physical or chemical manipulation of samples. However, mutations conferring toxicant resistance provide the opportunity for a novel biologically based TIE. Populations within the Hyalella azteca complex from pesticide-affected waterways were 2 and 3 orders of magnitude more resistant to the pyrethroid cyfluthrin and the organophosphate chlorpyrifos, respectively, than laboratory-cultured H. azteca widely used for toxicity testing. Three resistant populations, as well as laboratory-cultured, nonresistant H. azteca, were exposed to urban and agricultural runoff. Every sample causing death or paralysis in the nonresistant individuals had no effect on pyrethroid-resistant individuals, providing strong evidence that a pyrethroid was the responsible toxicant. The lack of toxicity to chlorpyrifos-sensitive, but pyrethroid-resistant, individuals suggested chlorpyrifos was not a likely toxicant, a hypothesis supported by chemical analysis. Since these mutations that confer resistance to pesticides are highly specific, toxicity to wild-type, but not resistant animals, provides powerful evidence of causality. It may be possible to identify strains resistant to even a wider variety of toxicants, further extending the potential use of this biologically based TIE technique beyond the pyrethroid and organophosphate-resistant strains currently available.
Collapse
Affiliation(s)
- Donald P Weston
- Department of Integrative Biology, University of California , Berkeley, California 94720, United States
| | - Helen C Poynton
- School for the Environment, University of Massachusetts , Boston, Massachusetts 02125, United States
| | - Kaley M Major
- School for the Environment, University of Massachusetts , Boston, Massachusetts 02125, United States
| | - Gary A Wellborn
- Department of Biology, University of Oklahoma , Norman, Oklahoma 73019, United States
| | - Michael J Lydy
- Center for Fisheries, Aquaculture, and Aquatic Sciences, Department of Zoology, Southern Illinois University , Carbondale, Illinois 62901, United States
| | - Christoph Moschet
- Department of Civil and Environmental Engineering, University of California , One Shields Avenue, Davis, California 95616, United States
| | - Richard E Connon
- Department of Anatomy, Physiology and Cell Biology, School of Veterinary Medicine, University of California , One Shields Avenue, Davis, California 95616, United States
| |
Collapse
|
13
|
Scheibener S, Conley JM, Buchwalter D. Sulfate transport kinetics and toxicity are modulated by sodium in aquatic insects. AQUATIC TOXICOLOGY (AMSTERDAM, NETHERLANDS) 2017; 190:62-69. [PMID: 28692867 DOI: 10.1016/j.aquatox.2017.06.027] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/10/2017] [Revised: 06/21/2017] [Accepted: 06/25/2017] [Indexed: 06/07/2023]
Abstract
The salinization of freshwater ecosystems is emerging as a major ecological issue. Several anthropogenic causes of salinization (e.g. surface coal mining, hydro-fracking, road de-icing, irrigation of arid lands, etc.) are associated with biodiversity losses in freshwater ecosystems. Because insects tend to dominate freshwater ecology, it is important that we develop a better understanding of how and why different species respond to salinity matrices dominated by different major ions. This study builds upon previous work demonstrating that major ion toxicity to the mayfly Neocloeon triangulifer was apparently due to the ionic composition of water rather than specific conductance. Synthetic waters with low Ca:Mg ratios and high SO4:Na ratios produced toxicity, whereas waters with higher Ca:Mg ratios and lower SO4:Na ratios were not toxic to mayflies at comparable conductivities. Here we used a radiotracer approach to show that Mg did not competitively exclude Ca uptake at environmentally realistic ratios in 4 aquatic insect species. We characterized SO4 uptake kinetics in 5 mayflies and assessed the influence of different ions on SO4 uptake. Dual label experiments show an inverse relationship between SO4 and Na transport rates as SO4 was held constant and Na was increased, suggesting that Na (and not Cl or HCO3) is antagonistic to SO4 transport. Based on this observation, we tested the hypothesis that increasing Na would protect against SO4 induced toxicity in a Na-dependent manner. Increasing Na from 0.7 to 10.9mM improved 96-h survivorship associated with 20.8mM SO4 from 44% to 73% in a concentration dependent manner. However, when Na reached 21.8mM, survivorship decreased to 16%, suggesting that other interactive effects of major ions caused toxicity under those conditions. Thus, the combination of elevated sulfate and low sodium commonly observed in streams affected by mountaintop coal mining has the potential to cause toxicity in sensitive aquatic insects. Overall, it is important that we develop a better understanding of major ion toxicity to effectively mitigate and protect freshwater biodiversity from salinization.
Collapse
Affiliation(s)
- Shane Scheibener
- Department of Biological Sciences, North Carolina State University, Raleigh, NC, USA
| | - Justin M Conley
- Department of Biological Sciences, North Carolina State University, Raleigh, NC, USA
| | - David Buchwalter
- Department of Biological Sciences, North Carolina State University, Raleigh, NC, USA.
| |
Collapse
|
14
|
Leung J, Witt JDS, Norwood W, Dixon DG. Implications of Cu and Ni toxicity in two members of the Hyalella azteca cryptic species complex: Mortality, growth, and bioaccumulation parameters. ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY 2016; 35:2817-2826. [PMID: 27081924 DOI: 10.1002/etc.3457] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/21/2015] [Revised: 01/05/2016] [Accepted: 04/11/2016] [Indexed: 06/05/2023]
Abstract
Hyalella azteca, an amphipod crustacean, is frequently used in freshwater toxicity tests. Since the mid-1980s, numerous organizations have collected and established cultures of H. azteca originating from localities across North America. However, H. azteca is actually a large cryptic species complex whose members satisfy both the biological and the phylogenetic species concepts. Genetic analysis at the mitochondrial COI gene has revealed that only 2 clades are cultured in 17 North American laboratories; however, there are 85 genetically divergent lineages within this complex in the wild. In the present study, 2 members (clades 1 and 8) of the H. azteca species complex were identified using the mitochondrial COI gene. These 2 clades were exposed to Cu or Ni for 14 d. A saturation-based mortality model and the general growth model were used to determine mortality (lethal concentration, 25% and 50% [LC25 and LC50], lethal body concentration, 25% and 50% [LBC25 and LBC50]) and growth (inhibitory concentration, 25% [IC25, IBC25]) endpoints, respectively. A modified saturation-based model was used to estimate metal bioaccumulation parameters. Clade 8 was significantly more tolerant than clade 1, with differences in LC50s. However, the effects of the metals on growth were not significantly different between clades, even though clade 1 was significantly larger than then clade 8. Differences in Cu or Ni bioaccumulation were not observed between clades 1 and 8. The differences in Cu and Ni LC50s may have implications for risk assessments, and it is recommended that toxicity experiments should only be performed with properly identified members of the H. azteca complex to maintain consistency among laboratories. Environ Toxicol Chem 2016;35:2817-2826. © 2016 SETAC.
Collapse
Affiliation(s)
- Jessica Leung
- Department of Biology, University of Waterloo, Waterloo, Ontario, Canada.
| | - Jonathan D S Witt
- Department of Biology, University of Waterloo, Waterloo, Ontario, Canada
| | - Warren Norwood
- Environment and Climate Change Canada, Burlington, Ontario, Canada
| | - D George Dixon
- Department of Biology, University of Waterloo, Waterloo, Ontario, Canada
| |
Collapse
|
15
|
Kennedy LM, Watson-Leung TL, Poirier DG. The evaluation of 3 diets for rearing Hyalella azteca and the influence of diet on acute ammonia toxicity. ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY 2016; 35:2416-2424. [PMID: 27061741 DOI: 10.1002/etc.3449] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2015] [Revised: 01/06/2016] [Accepted: 04/05/2016] [Indexed: 06/05/2023]
Abstract
Three Hyalella azteca cultures were reared on different diets since birth, reflecting the recommended diets of various investigators. The 3 diets consisted of fish flakes (FF), a mixture of fish flakes supplemented with the diatom Thalassiosira weissflogii (FF-D), and a mixture of fish flakes supplemented with yeast, cereal grass media, and trout chow (FF-YCT). The 3 diets were evaluated by comparing 20 wk of culturing data, along with the organism's response to standard 96-h toxicity testing with ammonium chloride over a range of pH and temperature. Hyalella azteca fed the FF-D diet had the highest overall survival rate (96.6%, standard deviation [SD] 4.3%) compared to those fed the FF diet (92.0%, SD 12.7%), or the FF-YCT diet (91.1%, SD 14.8%), although difference in survival was not statistically significant. Organisms fed the FF-D diet produced a higher number of young per week per adult (6.1, SD 2.8) than the FF diet (5.1, SD 2.2), or the FF-YCT diet (4.0, SD 1.2), although differences were not statistically significant. Of the diets evaluated, H. azteca reared on the FF-D diet were often significantly more resistant to total and un-ionized ammonia toxicity in acute 96-h testing than those reared on the other 2 diets across the 2 temperatures and 5 pHs tested, suggesting this may be the most optimal diet for this species. Environ Toxicol Chem 2016;35:2416-2424. © 2016 SETAC.
Collapse
Affiliation(s)
- Lisa M Kennedy
- Environmental Sciences and Standards Division, Laboratory Services Branch, Ontario Ministry of the Environment and Climate Change, Etobicoke, Ontario, Canada.
| | - Trudy L Watson-Leung
- Environmental Sciences and Standards Division, Laboratory Services Branch, Ontario Ministry of the Environment and Climate Change, Etobicoke, Ontario, Canada
| | - David G Poirier
- Environmental Sciences and Standards Division, Laboratory Services Branch, Ontario Ministry of the Environment and Climate Change, Etobicoke, Ontario, Canada
| |
Collapse
|
16
|
Soucek DJ, Dickinson A, Major KM. Selection of food combinations to optimize survival, growth, and reproduction of the amphipod Hyalella azteca in static-renewal, water-only laboratory exposures. ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY 2016; 35:2407-2415. [PMID: 26823001 DOI: 10.1002/etc.3387] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2015] [Revised: 01/06/2016] [Accepted: 01/26/2016] [Indexed: 05/12/2023]
Abstract
Although standardized sediment toxicity testing methods have been developed for the amphipod Hyalella azteca, no standardized chronic water-only toxicity testing methods have been established. Furthermore, optimal feeding and water quality conditions for culturing and toxicity testing with this species remained unclear. The objective of the present study was to determine the food or combination of foods that best promotes survival, growth, and reproduction of the US Lab strain of Hyalella azteca under 42-d, water-only, static-renewal testing conditions. The authors conducted 7 42-d control (no toxicant) tests with various combinations of food (including Tetramin, yeast-cereal leaves-trout chow, diatoms, wheatgrass, alfalfa, and maple leaves) and substrate types (clean "unconditioned" Nitex screens vs "conditioned" Nitex screens that were colonized by live biofilms). Over all treatments, survival ranged from 18% to 96%, dry weight per individual from 0.084 mg to 1.101 mg, and reproduction from 0 young/female to 28.4 young/female. Treatments that included Tetramin tended to result in better performance than those that did not. In particular, treatments that included Tetramin and either conditioned screens or diatoms consistently had high survival, weight, and reproduction values as well as low variability among replicates (measured as coefficient of variation). A ramped Tetramin plus diatom suspension feeding regime appears to have the greatest potential to produce consistently good performance across laboratories using static-renewal systems. Environ Toxicol Chem 2016;35:2407-2415. © 2016 SETAC.
Collapse
Affiliation(s)
- David J Soucek
- Illinois Natural History Survey, University of Illinois at Urbana-Champaign, Champaign, Illinois, USA.
| | - Amy Dickinson
- Illinois Natural History Survey, University of Illinois at Urbana-Champaign, Champaign, Illinois, USA
| | - Kaley M Major
- School for the Environment, University of Massachusetts-Boston, Boston, Massachusetts, USA
| |
Collapse
|
17
|
Soucek DJ, Dickinson A. Influence of chloride on the chronic toxicity of sodium nitrate to Ceriodaphnia dubia and Hyalella azteca. ECOTOXICOLOGY (LONDON, ENGLAND) 2016; 25:1406-16. [PMID: 27386878 DOI: 10.1007/s10646-016-1691-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 06/27/2016] [Indexed: 05/25/2023]
Abstract
While it has been well established that increasing chloride concentration in water reduces the toxicity of nitrite to freshwater species, little work has been done to investigate the effect of chloride on nitrate toxicity. We conducted acute and chronic nitrate (as sodium nitrate) toxicity tests with the cladoceran Ceriodaphnia dubia and the amphipod Hyalella azteca (chronic tests only) over a range of chloride concentrations spanning natural chloride levels found in surface waters representative of watersheds of the Great Lakes Region. Chronic nitrate toxicity test results with both crustaceans were variable, with H. azteca appearing to be one of the more sensitive invertebrate species tested and C. dubia being less sensitive. While the variability in results for H. azteca were to an extent related to chloride concentration in test water that was distinctly not the case for C. dubia. We concluded that the chloride dependent toxicity of nitrate is not universal among freshwater crustaceans. An additional sodium chloride chronic toxicity test with the US Lab strain of H. azteca in the present study suggested that when present as predominantly sodium chloride and with relatively low concentrations of other ions, there is a narrow range of chloride concentrations over which this strain is most fit, and within which toxicity test data are reliable.
Collapse
Affiliation(s)
- David J Soucek
- Illinois Natural History Survey, University of Illinois at Urbana-Champaign, 1816 S. Oak St, Champaign, IL, 61820, USA.
| | - Amy Dickinson
- Illinois Natural History Survey, University of Illinois at Urbana-Champaign, 1816 S. Oak St, Champaign, IL, 61820, USA
| |
Collapse
|
18
|
Soucek DJ, Mount DR, Dickinson A, Hockett JR, McEwen AR. Contrasting effects of chloride on growth, reproduction, and toxicant sensitivity in two genetically distinct strains of Hyalella azteca. ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY 2015; 34:2354-2362. [PMID: 26260521 DOI: 10.1002/etc.3070] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/19/2014] [Revised: 01/09/2015] [Accepted: 05/16/2015] [Indexed: 06/04/2023]
Abstract
The strain of Hyalella azteca (Saussure: Amphipoda) commonly used for aquatic toxicity testing in the United States has been shown to perform poorly in some standardized reconstituted waters frequently used for other test species. In 10-d and 42-d experiments, the growth and reproduction of the US laboratory strain of H. azteca was shown to vary strongly with chloride concentration in the test water, with declining performance observed below 15 mg/L to 20 mg/L. In contrast to the chloride-dependent performance of the US laboratory strain of H. azteca, growth of a genetically distinct strain of H. azteca obtained from an Environment Canada laboratory in Burlington, Ontario, Canada, was not influenced by chloride concentration. In acute toxicity tests with the US laboratory strain of H. azteca, the acute toxicity of sodium nitrate increased with decreasing chloride in a pattern similar not only to that observed for control growth, but also to previous acute toxicity testing with sodium sulfate. Subsequent testing with the Burlington strain showed no significant relationship between chloride concentration and the acute toxicity of sodium nitrate or sodium sulfate. These findings suggest that the chloride-dependent toxicity shown for the US laboratory strain may be an unusual feature of that strain and perhaps not broadly representative of aquatic organisms as a whole.
Collapse
Affiliation(s)
- David J Soucek
- Illinois Natural History Survey, Champaign, Illinois, USA
| | - David R Mount
- Mid-Continent Ecology Division, US Environmental Protection Agency, Duluth, Minnesota, USA
| | - Amy Dickinson
- Illinois Natural History Survey, Champaign, Illinois, USA
| | - J Russell Hockett
- Mid-Continent Ecology Division, US Environmental Protection Agency, Duluth, Minnesota, USA
| | | |
Collapse
|
19
|
Morphologically Cryptic Amphipod Species Are "Ecological Clones" at Regional but Not at Local Scale: A Case Study of Four Niphargus Species. PLoS One 2015; 10:e0134384. [PMID: 26226375 PMCID: PMC4520478 DOI: 10.1371/journal.pone.0134384] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2015] [Accepted: 07/08/2015] [Indexed: 11/19/2022] Open
Abstract
Recent studies indicate that morphologically cryptic species may be ecologically more different than would be predicted from their morphological similarity and phylogenetic relatedness. However, in biodiversity research it often remains unclear whether cryptic species should be treated as ecologically equivalent, or whether detected differences have ecological significance. In this study, we assessed the ecological equivalence of four morphologically cryptic species of the amphipod genus Niphargus. All species live in a small, isolated area on the Istrian Peninsula in the NW Balkans. The distributional ranges of the species are partially overlapping and all species are living in springs. We reconstructed their ecological niches using morphological traits related to feeding, bioclimatic niche envelope and species’ preference for epi-hypogean habitats. The ecological meaning of differences in niches was evaluated using distributional data and co-occurrence frequencies. We show that the species comprise two pairs of sister species. All species differ from each other and the degree of differentiation is not related to phylogenetic relatedness. Moreover, low co-occurrence frequencies in sympatric zones imply present or past interspecific competition. This pattern suggests that species are not differentiated enough to reduce interspecific competition, nor ecologically equivalent to co-exist via neutral dynamics. We tentatively conclude that the question of ecological equivalence relates to the scale of the study: at a fine scale, species’ differences may influence dynamics in a local community, whereas at the regional level these species likely play roughly similar ecological roles.
Collapse
|